Retainer for transporting and storing a segment of a stator adapted to be part of a generator of a wind turbine

ABSTRACT

A retainer for transporting and storing a segment of a stator which is part of a generator of a wind turbine includes a fastening device which is adapted to releasably fasten the segment to the retainer. The fastening device is attached to a base element of the retainer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of European Patent Application No.12158820.6 EP filed Mar. 9, 2012. All of the applications areincorporated by reference herein in their entirety.

FIELD OF INVENTION

A retainer for transporting and storing a segment of a stator adapted tobe part of a generator of a wind turbine is provided.

BACKGROUND OF INVENTION

Wind turbines known in the state of art may employ direct or indirectdrive configurations. A wind turbine using an indirect driveconfiguration comprises a transmission device or gear box fortransmitting and converting torque from a rotating rotor hub carrying aplurality of rotor blades and the generator converting mechanical energyto electrical energy. Another type wind turbines uses the direct driveconfiguration in which the torque directly transmitted to the generator.In either case, conversion of the mechanical energy to electrical energyis achieved by exerting a torque on the rotor which in turn rotatesrelative to a stator of the generator. The rotor carries a plurality ofpermanent magnets so that the rotation induces an electric current inconductive windings located on the stator by means of magneticinduction.

Wind turbines with a direct drive technology are promising due to theirreduced complexity and reduced number of components which in turnresults in a reduced overall weight of the wind turbine. As aconsequence, wind turbines of this type perform more reliable and needless service which makes them particularly suited for offshoreoperations.

The speed of the rotor blades inducing the torque upon the rotor hub islimited. Consequently, the rotational speed of the rotor hub is limited.This may cause problems in particular when the wind turbine is directlydriven. In order to allow for a sufficient number of pole changes pertime slot when generating electrical power, the rotor and the stator ofthe generator have to be provided with relative large diameters. Inparticular, the rotor has to be large enough to carry enough permanentmagnets inducing the pole changes. As a consequence, generators used fordirectly driven wind turbines may have a diameter of several meters,i.e. five to six meters and weigh several tons. Transport, handling andservicing of such large and heavy generators is challenging.

It is common practice to facilitate handling of such a generator bydividing the stator into several segments. For example, the stator maybe built from six segments each making up for a 60° section of theannular stator. During assembly of the generator, the segments of thestator are mounted to mounting structure or bedframe. The mountingstructure carrying the stator is then connected to the rotor through abearing wherein the rotor surrounds the stator. Alternatively, thestator may be arranged so as to surround the rotor.

As for now, the transport of the segments of the stator, in particularfrom the production facility to the assembly location of the generator,is performed by utilising standard means of transport, i.e. pallets.However, it turned out that this way of transporting the segment bearsan inherent high risk of mechanical damage. In particular, theconductive windings of the segments typically made from a metal likecopper are easily deformed and damaged. Malfunctioning segments areexpensive and time consuming to repair. Damages introduced duringtransport or handling of the segments may include short circuits thatare difficult to locate and/or to repair.

SUMMARY OF INVENTION

It is an object to provide a transport apparatus suitable for storingand transporting segments of a stator adapted to be part of a generatorof a wind turbine that in particular may reduce the risk of damagescaused by mechanical shocks or the like.

The object is achieved by a retainer of the aforementioned type, whereina fastening device adapted to releasably fasten to the segment isattached to a base element of the retainer.

The retainer provides a cost effective means reducing damage of thesegments stored therein during transport and storage. The retainer mayalso be used as an aid during assembly of the generator. Duringtransport, the segment typically rests on the fastening device thatfastens the base element of the retainer to the segment. Thus, relativemotion of the segment with respect to the base element is at leastreduced during transport. As a consequence, the introduction ofmechanical shocks to the segments is suppressed which results in lessdamages. Cost and effort of repairs are reduced accordingly.

The retainer is designed as a heavy duty receptacle adapted to retainsegments weighing several tons, in particular 3 to 5 tons, even moreparticularly about 4 tons. The retainer may have an unladen weight 750kg to 1.5 tons. Respectively, the sides of the rectangular base elementmay have dimensions of 2 m to 3 m.

The fastening device may be adapted to engage the segment with positivelocking. In particular, positive locking may be achieved bycorrespondingly shaped mating structures. In one embodiment, thefastening device comprises at least one protrusion adapted to snugly fitinto a corresponding recess arranged on the segment. Alternatively, theprotrusion may be arranged on the segment so that the protrusion mayengage the recess disposed on the fastening device. In either case, theat least one protrusion is arranged to engage and disengage the at leastone recess so as to respectively fasten the base element of the retainerto the segment and unfasten the segment from the base element of theretainer. The form fit between the segment and the fastening deviceprovides a particularly simple but effective means to reduce damagesduring transportation. Accordingly, the retainer has a simple designthat may be cost-efficiently manufactured in high quantities.

According to a preferred embodiment, the fastening device comprises atleast one translatable member mounting at least one bolt adapted toengage the segment with positive locking. The translatable member and/orthe at least one bolt may be made from a durable material, in particularan alloy or a metal. Even more particularly, the at least one boltand/or the translatable member may be made from steel, so that a formfit is provided that is capable of sustaining the substantial weight ofthe segment when the retainer locked to the segment is flipped upsidedown for positioning a segment during assembly of the generator. Hence,the retainer may be additionally used as a tool during assembly of thestator facilitating safe handling. Preferably the bolt or each boltengages a hole in a stator frame of the stator segment, which comprisesthe frame and lamination and coils or windings attached to it.

In a further development, the translatable member is translatablyarranged relative to a frame of the fastening device. The frame isprovided with sufficient stability so that it may support and carry theweight of the segment. Translation of the translatable member relativeto the frame of the fastening device causes the at least one boltmounted thereto to engage or disengage the recess disposed in thesegment. Thus, the translatable arrangement provides a releasableconnection capable of locking the segment to the retainer. The retainermay be used a several times further enhancing cost-effectiveness andreducing the negative impact on the environment that is inherent to theuse of the disposal packaging material.

In a preferred embodiment, the translatable member is adapted to betranslated upon actuation of an actuating device. In the context of thispatent, actuation is a process induced by a person, in particular theaction of the person operating the actuation device so as to fasten thesegment to the retainer or release the segment from the retainer.Accordingly, the actuation device may be adapted to be manually operatedby the person. In particular, the actuation device may comprise one ormore lever arms adapted to displace the at least one translatable memberrelative to the segment. Alternatively, manual actuation of theactuation device may require the use of a tool like, for example, ascrew driver or the like.

In one preferred embodiment, the actuating device comprises a rotatablemember, in particular a screw, adapted to translate the translatablemember upon rotation. The rotatable member may comprise a thumbscrewadapted to be manually operated by the person. Alternatively, therotatable member may be engaged by a corresponding tool, even moreparticular by a suitable handheld power tool like an electric orpneumatic screw driver. The actuating device is accessible to beactuated from the exterior of the retainer. The retainer may compriseside walls with access openings allowing for access to the rotatablemember from outside. Alternatively, the rotatable member may be arrangedas a turn pin projecting through the access opening so that it mayactuated when needed.

It is beneficial to attach the fastening device indirectly to the baseelement of the retainer via at least one intermediately arrangeddampening means. The dampening means may comprise one or more dampeningelements that are configured to at least reduce mechanical shocksintroduced to the segment resting on the fastening device duringtransport. The dampening means may in particular be arranged so as toreduce vibrations introduced to the segment during transport. Accordingto different embodiments, the dampening means may comprise springelements like coil springs or leave springs. Alternatively, dampeningmeans may comprise elements made from a deformable material having asuitable module of elasticity.

Preferably, the dampening means is made from an elastomer. One or moreelements comprising the dampening means may be made from the elastomer,in particular rubber. The dampening means may be arranged as rubber padsvulcanised to both the base element of the retainer and the frame.

In another alternative embodiment, a plurality of first dampeningelements made from the elastomer is form fitted to the frame of theretainer. Each first dampening element engages a second dampeningelement made from the elastomer and form fitted to the base surface ofthe retainer.

The connection between the dampening means and the base element and/orthe fastening means is preferably a form fit that allows forcompensation of relative movement of the base element relative to theframe fastened to the segment of the stator. Thus, vibrations occurringduring transport of the segment may be compensated.

In embodiments comprising dampening means made from the elastomer,additional connection means is provided that connects the frame to thebase element of the retainer. The additional connections means providesa backup secure connection that mounts the frame to the base elementeven if the dampening means fails or breaks. In one embodiment, theconnection means comprises a pin having a flange that is retained in acylinder. According to alternative embodiments the pin is firmlyconnected to the frame or the base element, whereas the cylinder isfirmly connected to the other of the frame or the base element. Theflange and the cylinder form a limit stop limiting a maximumdisplacement of the frame relative to the base element. The dampeningmeans may be made from an elastomer prone to fatigue of material. Thus,the dampening means may break when the retainer is repeatedly used fortransport of segments. The connection means provide a secure backupsolution so that the segment may be transported to the assembly locationeven when the dampening means already failed.

In a preferred embodiment, a wall structure extends perpendicularly fromthe planar base element. The wall structure is adapted to at leastpartially surround the segment of the stator. The wall structureprovides a protective encasing for the segment further reducing the riskof mechanically damaging the segments during transport or storage.

Preferably, corresponding mating structures are arranged on a top faceof the wall structure and on a bottom face of the base element. Themating structures are adapted to positively engage each other when oneretainer is stacked upon another retainer. Advantageously, a pluralityof retainers, each carrying a segment of the stator, is stacked uponeach other during transport. This allows for an optimal use of spaceprovided, for example in a cargo container, truck or the like. The formfit between the retainers stacked upon another furthermore providesstability during transport further reducing the risk of damaging thesegments.

In particular, a male member is arranged on the top face of the wallstructure or on the bottom face of the base element and a female memberis arranged on the other of the top face of the wall structure or thebottom face of the base element. The male member of the retainer isadapted to positively engage the female member of an adjacent retainer.Thus, corresponding mating structures are provided that positivelyengage each other so as to provide stability for arrangements of stapledretainers. The base element may have a rectangular shape and the wallstructure may comprise four pillars having a dimension extendingperpendicular from the base element, wherein each pillar is arranged inone corner of the rectangular base surface. In particular, the male orfemale members of the mating structure may be arranged on the top facesof the pillars.

In an embodiment, the wall structure comprises side walls arrangedaround the borders of the rectangular base element, wherein at least twoside walls arranged along the opposite sides of the rectangular baseelement have dimensions extending perpendicular from the base elementthat correspond to at most half of the dimension of the pillars. Theother side walls may have a dimension extending perpendicular from thebase element of at most the dimension of the pillars. In particular, theside walls with the smaller dimensions are arranged along the longersides of the rectangular base element. This retainer is designed to betransported in a very efficient way when empty. In particular, a nestedarrangement of retainers stacked upon another may be achieved, whereinone retainer is rotated with respect to an adjacent retainer around anaxis normal to the rectangular base element and flipped upside down. Acompact and nested arrangement of two empty retainers stacked uponanother is achieved. Thus, available space is optimally used, inparticular when empty retainers are stored or transported which in turnallows for, in particular, reduction of transportation costs.

The retainer with connecting portions may be adapted to be accessed by ameans of lifting and positioning, in particular a fork of a fork lift.The connecting portions are arranged on the base element. In particular,the connecting portions may be arranged as two channels extendingparallel to each other so that the fork of the fork lift may beintroduced into the channels from one side. Each connecting portionforms a substantially closed structure so that, when the fork isintroduced into the connecting portion, a support is provided in amanner that allows for turning the retainer whilst being held only bythe fork engaging the connecting portions. The retainer and the segmentlocked thereto may be turned around an arbitrary angle around an axisdefined by the parallel connecting portions. This may be used toposition the segment of the stator retained in the retainer duringassembly of the generator. In particular, a placement of the segment ofthe stator onto a segment trolley in the proper direction may be easilyachieved by the use of a fork lift or the like capable of turning thefork around an angle. Thus costs and effort of assembly of the stator isreduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view of a retainer with a segment of a stator.

FIG. 2 shows a first sectional view of the retainer with the segmentretained therein.

FIG. 3 shows a second sectional view of the retainer with the segment.

FIG. 4 shows an isometric view of the retainer having a fastening deviceconnected to a base element.

FIG. 5 shows a detailed view of the fastening device comprising atranslatable member slidably arranged relative to a frame.

FIG. 6 shows another isometric view of the fastening device comprisingthe frame with the translatable member.

FIG. 7 shows an isometric view of six empty retainers stacked uponanother.

FIG. 8 shows an arrangement of the three retainers upon another, whereinone segment of the stator is retained in each retainer.

FIG. 9 shows a segment trolley and an assembly device used duringassembly of the stator.

Corresponding parts are indicated in all figures by the same referencesymbols.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a retainer 1 with a segment 2 of a stator. The segment 2 islocked to the retainer 1. The retainer 1 comprises a substantiallyrectangular base element 3 and a wall structure extending from the baseelement 3 in a perpendicular direction. The wall structure comprisesfour side walls 4 arranged along sides of the rectangular base element 3and four pillars 5 respectively arranged in corners of the rectangularbase element 3.

A female member 6 arranged as a recess is located on a top face of eachpillar 5. Respectively, male members 7 are arranged on a bottom face ofthe base element 3. Each male member 7 is located in one of the cornersof the rectangular base element 3 and projects from the base element 3downwards. The male member 7 and the female member 6 are designed as amating structure. Male and female member 7, 6 of retainers 1 stackedupon another engage each other with positive locking. The form fitprovides stability of the arrangement of stacked retainers 1, inparticular versus lateral displacement during transport of the segments2.

In the exemplary embodiment shown in the figures, the retainer 1 isdesigned as a heavy duty receptacle adapted to retain a segment 2weighing several tons, in particular 3 to 5 tons, even more particularlyabout 4 tons. The retainer 1 has an unladen weight of about 1 ton. Thearea of the rectangular base element 3 measures 2.3 m×2.1 m.

As can be seen in FIG. 1, the side walls 4 surround the segment 2retained in the retainer 1. The side walls 4 arranged along the longersides of the rectangular base element 3 have a height that is smallerthan the height of the side walls 4 arranged along the shorter sides ofthe rectangular base element 3. In this context, the term height isunderstood as the dimension extending perpendicular to the base element3. The height of the side walls 4 arranged along the longer sides of thebase element 3 is less than half of the height of the pillars 5 arrangedin the corners. The side walls 4 arranged along the longer sides of therectangular base element 3 have larger dimensions and reach almost theheight of the pillars 5.

The retainer 1 further comprises connecting portions 8 that are arrangedon the base element 3. The connecting portions 8 are shaped as twochannels extending parallel to each other. The connecting portions 8 areadapted to be engaged by a means for lifting and positioning theretainer, in particular a fork of a fork lift.

Additionally, access openings 11 are disposed in side walls 4 oppositeto each other. Each access opening 11 is adapted to be accessed by atool, in particular a screw driver, so as to actuate an actuation device15 that is shown in more detail in FIGS. 4 to 6 arranged within theretainer 1.

FIG. 2 shows the retainer 1 with the segment 2 in a sectional andperspective view. The connecting portions 8 form a raised structure onthe base element 3. A fastening device 9 is arranged on top of theconnecting portions 8. The fastening device 9 is adapted to engage thesegment 2 with positive locking.

FIG. 3 shows another isometric and sectional view of the retainer 1carrying the segment 2. The segment 2 comprises a support structurecomprising a plurality of support means 10 each having a T-shaped crosssection.

FIG. 4 shows an empty retainer 1 in an isometric view. A fasteningdevice 9 is attached to the base element 3 of the retainer 1. Thefastening device 9 is surrounded by the side walls 4 and comprises aframe 12 and two translatable members 13 slidably arranged relative tothe frame. Each translatable member 13 comprises a plurality of bolts 14that jointly move when the translatable member 13 is translated uponactuation of the actuation device 15. The actuation device 15 comprisesa rotatable member 16 that works in a manner similar to an adjustablescrew. Accordingly, the translatable member 13 shaped as a jaw istranslated upon rotation of the rotatable member 16. The rotatablemember 16 may be engaged by an appropriate tool that is inserted intothe access opening 11.

The fastening device 9 is adapted to releasably fasten the segment 2 tothe retainer 1. In order to reduce mechanical shocks or vibrationsintroduced to the segment 2 locked onto the fastening device 9 duringtransport; the fastening device 9 is connected to the base element 3 viadampening means. The dampening means are adapted to at least partiallyabsorb vibrations or the like and comprise dampening elements 17 madefrom an elastomer. Each dampening element 17 is arranged as a rubber padwherein each rubber pad engages the frame 12 of the fastening device 9and the base element 3 of the retainer 1 in a form fit. Form fit isachieved by a process of vulcanisation, whereby opposite ends of thedampening element 17 are connected respectively to the frame 12 and tothe base element 3.

Additionally, a connection means 18 mounts the frame 12 of the fasteningdevice 9 to the base element 3 of the retainer 1. The connection means18 provides a backup solution that attaches the fastening device 9 tothe retainer 1 in case that connection established by the elastomericdampening elements 17 breaks or fails otherwise.

The fastening device 9 with its components is illustrated in more detailin FIG. 5. The translatable member 13 shown in FIG. 5 is displaced withrespect to the frame 12 so that the bolts do not project from the frame12 in a lateral direction. This corresponds to an unlocked position ofthe fastening device 9.

The additional connection means 18 comprise a pin 19 having a flange 20and a cylinder 21. The pin 19 is firmly connected to the base element 3of the retainer. The cylinder 21 is firmly connected to the frame 12 ofthe fastening device 9. The pin 19 is slidably received within thecylinder 21 so that a slight displacement of the fastening device in adirection normal to the base element 3 is possible. Maximal displacementof the frame 9 with respect to the base element 3 is limited by a limitstop provided by the flange 20 of the pin 19 abutting against thecylinder 21.

FIG. 6 shows the translatable member 13 arranged in the locked position,wherein the bolts 14 adapted to engage corresponding recesses disposedin the segment 2 of the stator project laterally from the frame 12 ofthe fastening device 9.

The segment 2 is fastened to the retainer 1 by arranging the segment 2onto the fastening device 9 while the translatable member 13 ispositioned in the unlocked position illustrated in FIG. 5. The actuationdevice 15 is then actuated and the translatable member 13 is translatedfrom the unlocked position to the locked position illustrated in FIG. 6by rotating the rotatable member 16. In the locked position, the bolts14 engage corresponding recesses disposed in the segment 2 with positivelocking. The form fit between the fastening device 9 and the segment 2provides a secure connection so that the segment may, for example, besafely transported to an assembly location.

FIG. 7 shows an arrangement of several empty retainers 1 stacked uponanother. The rectangular design of the retainers 1 and the arrangementof low side walls 4 arranged along the longer sides of the rectangularbase element 3 allows for a nested arrangement that minimises therequired space during storage and transport. Nested arrangement isachieved by flipping the retainer 1 stacked upon another retainer 1upside down and rotating the retainer 1 flipped upside down about anangle of 90° around an axis extending normal to the base element 3. Inthis configuration the side walls 4 having the smaller dimension of theadjacent retainers 1 abut on each other.

FIG. 7 shows an arrangement of six empty retainers 1 stacked upon eachother in a nested arrangement. The stacked retainers 1 exhibit a heightsmaller than the height of a standard container so that available spaceis optimally used.

FIG. 8 shows an arrangement of three retainers 1 each carrying onesegment 2 of the stator in a perspective view. The retainers 1 arestacked upon another, wherein form fit established by the female members6 and male members 7 illustrated in more detail in FIG. 1 providesstability during transport of the segments 2.

FIG. 9 shows in an exemplary illustration of an assembly device 22 and atrolley 23 carrying a segment 2. The segment 2 may be positioned on thetrolley 23 whilst still being locked to the retainer 1. To do so, theconnecting portions 18 are engaged by a fork of a fork lift and theretainer 1 carrying the segment 2 is flipped over. The closed connectionportions 8 of the retainer 1 allow for a turning of the segment 2 whilststill being connected to the retainer 1. The segment 2 is positioned inthe proper orientation onto the trolley 23 before the fastening device 9is unlocked by actuating the actuation device 15. Afterwards, theretainer 1 may be removed.

For assembly, the segment 2 is mounted to a mounting structure 24 orbedframe which is rotatably arranged on the assembly device 22. Thesegments 2 may be moved with the help of the trolley 23 into a positionsuitable for assembly.

While specific embodiments have been described in detail, those withordinary skill in the art will appreciate that various modifications andalternative to those details could be developed in light of the overallteachings of the disclosure. For example, elements described inassociation with different embodiments may be combined. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andshould not be construed as limiting the scope of the claims ordisclosure, which are to be given the full breadth of the appendedclaims, and any and all equivalents thereof. It should be noted that theterm “comprising” does not exclude other elements or steps and the useof articles “a” or “an” does not exclude a plurality.

We claim:
 1. A retainer for transporting and storing a segment of astator adapted to be part of a generator of a wind turbine, comprising:a base element, and a fastening device attached to the base element,wherein the fastening device releasably fastens the segment to theretainer.
 2. The retainer according to claim 1, wherein the fasteningdevice engages the segment with positive locking.
 3. The retaineraccording to claim 2, wherein the fastening device comprises at leastone translatable member with at least one bolt adapted to engage intothe segment with positive locking.
 4. The retainer according to claim 3,wherein the at least one translatable member is translatably arrangedrelative to a frame of the fastening device.
 5. The retainer accordingto claim 3, wherein the at least one translatable member is adapted tobe translated upon actuation of an actuating device.
 6. The retaineraccording to claim 5, wherein the actuating device comprises a rotatablemember adapted to translate the translatable member upon rotation. 7.The retainer according to claim 6, wherein the rotatable member includesa screw.
 8. The retainer according to claim 1, wherein the fasteningdevice is indirectly attached to the base element via at least oneintermediately arranged dampening unit which comprises an elastomer. 9.The retainer according to claim 8, wherein a connection between thedampening unit and the base element and/or the fastening device is aform fit connection.
 10. The retainer according to claim 1, furthercomprising: a wall structure which extends perpendicularly from the baseelement and at least partially surrounds the segment.
 11. The retaineraccording to claim 10, wherein corresponding mating structures arearranged on a top face of the wall structure and on a bottom face of thebase element, and wherein the mating structures are adapted topositively engage each other when a first retainer is stacked upon asecond retainer.
 12. The retainer according to claim 11, wherein a malemember is arranged on the top face of the wall structure or on thebottom face of the base element of the first retainer, wherein a femalemember is arranged on a top face of a wall structure or a bottom face ofa base element of the second retainer, and wherein the male member ofthe first retainer is adapted to positively engage the female member ofthe second retainer when stacked upon the first retainer.
 13. Theretainer according to claim 10, wherein the base element has arectangular shape and the wall structure comprises four pillars having adimension extending perpendicular from the base element, and whereineach pillar is arranged in one corner of the rectangular base element.14. The retainer according to claim 13, wherein the wall structurecomprises side walls arranged around borders of the base element,wherein at least two side walls are arranged along opposite sides of therectangular base element having dimensions extending perpendicular fromthe base element, wherein the dimensions correspond to at most half ofthe dimension of the pillars.
 15. The retainer according to claim 1,wherein connecting portions are arranged on the base element and areadapted to be accessed by a lifting device.
 16. The retainer accordingto claim 15, wherein the lifting device comprises a fork of a fork lift.17. The retainer according to claim 3, wherein the at least one bolt ofthe fastening device engages in a hole in a frame of the stator segment,wherein a lamination and coils and/or windings of the stator areattached to the frame.